Design

7.5.2 Ways to Improve Loading Capacity

• Constructive design
  o compressive stress is preferable in ceramic parts and can be achieved through appropriate
     - specification of how the load is applied,
     - part design,
     - the positioning of joints and contact points
  o creating compressive pre-stress to compensate for tensile stresses during use, for example by
     - casting metal around the ceramic,
     - shrink-on bushings/sleeves on rotationally symmetrical ceramic parts,
     - pre-stressing when assembled,
     - technological measures (e.g. glazing high tension insulators).
  o increasing the loading area, avoiding stress concentrations,
  o dividing large-volume parts into several pieces (modular construction). consideration of the effect of volume on the strength, in particular if the Weibull modulus m < 20.
  

• Choosing a different material
  o using a material with higher strength,
  o using a material with greater KIC-value (greater crack resistance),
  o using dispersion-strengthened material (e.g. aluminium oxide reinforced with zirconium oxide),
  o using fibre-reinforced materials.
  

• Technological measures
  o machining only in a direction parallel to the direction of maximum stress,
  o creating compressive stress in the surface region,
  o controlling and exploiting transformation processes in the crystal structure, especially when using zirconium oxide.